We would do all that in EMT inside around here. If the basement is open it should not take long. I would figure 1/2 a day with 2 workers. $75 x 8 = $600. $150 should be more then enough in material and could cover some GFCI breakers, #12 wire with EG, pipe, box, in use cover, MU. I got $750. For trenching and back filling I would add another $300.